Author Topic: 76 XS500 rear disk brake adjustment?  (Read 2067 times)

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Offline Mystery

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76 XS500 rear disk brake adjustment?
« on: February 08, 2016, 11:42:48 PM »
The rear disk brakes on my 76 XS500 are starting to bind.  This has been getting slowly worse with time and I have to address it as its my daily commuter.  there is the correct amount of play in the rear brake pedal, is there an adjuster that Im not seeing mention of that will allow me to relax the piston, freeing the brake pads?  Or is this indicative of needing a rebuild?  Also, Im not able to find good instruction on how to replace the brake pads, if I need to do this. any links?

Thanks!!

Chris

Offline dave835

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Re: 76 XS500 rear disk brake adjustment?
« Reply #1 on: February 09, 2016, 04:05:37 AM »
      Put your bike on the center stand , and operate the brake . If it is dragging , open the bleeder valve on the caliper
and see if that allows the brake to release fully . If that doesn't help , check to see if the caliper can move on it's
slide pins. Check the wear on the pads ; they should wear fairly evenly . Stuck pins will usually wear the pad opposite
the caliper piston .
     If the brake releases by opening the bleeder , you are having a fluid return issue . If the fluid is rusty colored ,
the return port in the master cyl. could be blocked . Rarely but occasionally the flex line can block internally .These usually cause the brake to drag harder as the brake gets
hotter . dirty/rusty fluid can also seize the caliper piston , which would not allow the brake to release fully all the
time .

Offline guylr

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Re: 76 XS500 rear disk brake adjustment?
« Reply #2 on: February 09, 2016, 02:19:06 PM »
/\ Good advice.

Guy
Now Retired Yamaha guy. Cut me and I bleed "Cinquasia Red"

Offline wilberforce

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Re: 76 XS500 rear disk brake adjustment?
« Reply #3 on: February 10, 2016, 01:36:15 PM »
Years ago (don't laugh) I found the back brake on my '78 model was getting more and more easy to lock the wheel, to the extent that I wasn't using the back brake.

I let a touch of air into the sytem and it made some difference, but I wasn't using it very much, may  be not a greta idea, but it worked for me.

I subsequently decided recently to strip the system totally and rebuild, now I have a very usable back brake.  The issues I had were getting the master cylinder off the bike as I ended up snapping one of the bolts holding it on, and then getting fluid to flow back throught the system, but I persevered.


I don't think there is any actual adjustment possible.


One of the Boys from the Wall.
XS500E - 1978 vintage
Aprillia Shiver 750 - 3,600 miles.
Moto Guzzi Breva V750ie - 2005 vintage - sold.

Offline Mystery

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Re: 76 XS500 rear disk brake adjustment?
« Reply #4 on: February 12, 2016, 09:06:24 PM »
Is anyone aware of a step by step guide for removing calipers and replacing brakes? I have to take the brake apart and likely rebuild. Thinking the piston is stuck.